Anion exchange resins from cross-linked halogenated polyvinylaromatic polymers



ANION EXCHANGE RESINS FROM CROSS-LINKED HfilfigGENATED POLYVINYLAROMATIC POLY- Albert H. Greer, Westmont, N. J., and Martin E. Gilwood, Oceanside, N. Y., assignors to The Pei-merit (Iornpany, New York, N. Y., a corporation of Delaware No Drawing. Application April 21, 1953, Serial No. 350,266

27 Claims. (Cl. 260-2.1)

The present invention relates to novel, synthetic polymeric compositions which are useful in the removal of anions from aqueous solutions and to a novel process for preparing said compositions. The invention also relates to a method of removing anions from an aqueous solution.

Anion exchange resins, in order to be satisfactory for use, must be substantially insoluble in water, dilute acids and alkalies. They must be capable of resisting physical transformation, such as undue swelling, or mechanical disintegration, such as spalling or shattering of the resin beads and granules, when in contact with the solution they are used to treat. They must also have a high useful or operating capacity for removing anions from aqueous solutions, and be capable of being repeatedly regenerated for reuse when they become exhausted. It is also desirable that in addition to a high operating capacity, the resin have a high capacity for removing the weaker anions from solution, such as silica and carbon dioxide. The present invention makes it possible to obtain anion exchange resins which have a significant enhancement in operating capacity, as well as concomitant improvement in other desirable properties, over those of the anion exchange resins with which the prior art is familiar.

it is an object of the present invention to provide novel anion exchange resins which, while possessing all of the essential properties of a successful anion exchange resin, possess an unuually high operating capacity as well as a high capacity for the removal of weaker anions from aqueous solutions.

It is an additional object of the present invention to provide a means for enhancing the operating capacity, and other capacities and properties, of anion exchange resins over those of related anion exchange resins of the prior art.

It is a further object to provide a novel process for the removal of anions, and especially weaker anions, from aqueous solutions.

It is an additional object to provide a novel process for producing the novel anion exchange resins of the present invention.

Other objects will be apparent to those skilled in the art from a reading of the description which follows.

In U. S. Patents Nos. 2,631,999; 2,632,000 and 2,632,001 to McMaster et al. are described anion exchange resins which are quaternary ammonium derivatives of a haloalkylated, halogenated copolymer resin of a polyvinyl aromatic hydrocarbon and certain monovinyl aromatic hydrocarbons. The haloalkylated, halogenated nited States Patent copolymer resins described in the patents contain halogen ice mer resin of a monovinyl aryl compound and a diunsaturated aliphatic crosslinking compound of the invention in which the halogenated copolymer resin contains up to 4.0% halogen have a significantly increased operating capacity over otherwise equivalent anion exchange resins in which the halogen content of the copolymer resin is 7.7% or greater. The operating capacity of the-anion exchange resins of the present invention is also significantly greater than an otherwise equivalent anion exchange resincontaining no halogen in the copolymer resin.

The present invention comprises a water insoluble anion exchange resin which is an amino-alkyl or quaternary ammonium-alkyl derivative of a halogenated copolymer of a monovinyl aryl compound and a diunsaturated aliphatic cross-linking compound; said halogenated copolymer con taining no more than 4.0% halogen. The quaternary ammonium-alkyl derivatives are preferred since they are more highly basic and are more effective in adsorbing weaker anions. The quaternary ammonium and amine groups may be substituted with alkyl, aralkyl or alkanol groups. The amine groups may be primary, secondary or tertiary amine groups. It is desirable that, in any event, the alkyl, aralkyl and alkanol groups be of the lower" category, i. e., each having 8 or less carbon atoms and in the case of alltyl and alkanol groups, preferably not more than 4 carbon atoms each. The preferred lowing group:

in which R1, R2 and R3 are alkyl, alkanol and aralkyl groups as defined above. It is an integer of value from 1 to 4. Best results are obtained where n: is 1 and the CnH2n-group is a methylene group. Y is an anion, preferably one of a mineral acid, such as chloride, bromide, sulfate, etc., or when in the anion exchanging condition, is a hydroxyl group. The anion exchange resins of the invention have excellent properties for adsorbing weak anions when one or both of R1 and R2 are lower alkanol group, particularly where one or both of these groups is the ethanol group.

In preparing the anion exchange resins of the invention, we begin with the preparation of a halogenated copolymer of a monovinyl aryl compound and a dimsaturated aliphatic crosslinking compound. The monovinyl aromatic compounds are suitably vinyl aromatic hydrocarbons, such as styrene, ortho-, metaand paramethyl and ethyl styrenes, vinyl naphthalene, vinyl anthracene and the homologues of these compounds. Styrene is preferred. Also, the monovinyl aryl moiety of the copolymer may consist of nuclear substituted chlorine or bromine substituted vinyl aryl compounds, such as the ortho-, metaand parachloro and bromo styrenes copolymerized with other diluting monovinyl aryl compounds. The concentration of the halogenated monovinyl aryl compound in the copolymer should be adjusted to provide a halogen concentration of less than 4.0% in the copolymer resin.

Among the diunsaturated aliphatic crosslinking compounds which may be used are compounds containing two or more vinyl groups, such as the following: divinyl sulfone; divinyl ketone; vinyl ethinyl hydrocarbons, such as vinyl acetylene and divinyl acetylene; vinyl maleate; vinyl esters of acrylic, methacrylic and ethacrylic acids, such as vinyl acrylate, vinyl methacry-late and vinyl ethacrylate; divinyl esters of dibasic acids, such as divinyl oxalate, divinyl maleate, divinyl malonate and divinyl succinate; and acrylic diesters of an aliphatic polyhydric alcohol, such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, glycerine dimethacrylate and ethylene glycol diacrylate. Compounds havingv other unsaturated aliphatic groups than the vinyl group may be used, although the group should preferably have aterrninal double bond. Among such groups which may be used to replace the vinyl group are the allyl group, the 3-n-butenyl group, etc.

The copolymer resins for use in the invention shall contain a predominant amount, on a molar basis, of the monovinyl aryl compound or, stated in another Way, more than half of the total number of moles of reactants in preparing the copolymer shall be monovinyl aryl compounds. It is preferred that the monovinyl aryl compound constitute from 60 to 99.9%, on a molar basis, of copolymer. Therefore, the unsaturated aliphatic crosslinker compounds should constitute from 0.1 to 40% of the mixture on a molar basis. Increased amounts of crosslinking compounds produce a copolymer which is increasingly dense and which becomes correspondingly difficult to haloalkylate in subsequent steps. Best results are obtained where the monovinyl aryl moiety constitutes from 85.0 to 99.5% of the copolymer resin and the crosslinker from 0.5 to (both on a weight basis). The optimum compositions of the copolymer resin are those prepared from about 4-10% by Weight of aliphatic crosslinker compound and 90-96% by weight of monovinyl aryl compound. A polymerizate or copolymer resin having a particle size range of betweenl5 to 60 mesh is most desirable.

The polymerization of the copolymer resin for use in the invention is conducted in the presence of well known oxidizing catalysts. These catalysts include ozone, oxygen, organic peroxides, such as acetyl peroxide, tertiary-butyl hydroperoxide, benzoyl peroxide, hydrogen peroxide, the so-called per salts, such as the Water soluble per-sulfates, and the azoketonitriles such as ambisisobutyronitrile and azobiscyclopropriopropylnitrile. The catalyst may be employed in suitable amounts ranging from 0.1% to about 2.0% by Weight based on the weight of monomeric material to be polymerized.

During the polymerization of the copolymer resin, it may be advisable to add suspending agents, such as gelatine, and vegetable gums, such as carboxymethylcellulose, methylcellulose or casein, and small amounts of other materials, such as boric acid.

If the copolymer resin does not already contain halogen as a result of incorporating a halogen-bearing component into the copolymer resin or if the copolymer resin does not'contain the desired amount of halogen, halogen is' next introduced into the resin in desired amounts. The halogenating agents may be elemental chlorine or bromine with the use of the common halogenating catalysts, such as iodine, ultraviolet light, etc. Those anion exchange resins prepared by catalyzing the elemental halogenation with ultraviolet light demonstrate'improved mechanical stability and resistance to shattering and breaking of the particles upon repeated usage and regeneration. The halogen'ation of the copolymer may be accomplished by the halogen containing inorganic halogenating reagents, sulfuryl chloride, sulfuryl monochloride, phosphorus pentachloride, phosphorus pentabromide, etc., with or Without the presence of peroxide catalysts. The copolymer resin is halogenated until it contains the desired amount of halogen, although in no case have the benefits of the present invention been realized where the halogen content exceeds about 4.0% of the weight of the copolymer resin.

It has been discovered that the benefits of the present invention may be realized in varying degrees, depending on the concentration of halogen in the copolymer resin. The copolymer should, however, contain from.0.2% to 4.0% halogen. Where the halogen in the copolymer resin is introduced solely as nuclear substituted halogen by means of copolymerizing a chlorostyrene in preparing furyl chloride and phosphorus pentachloride, subsequent to the polymerization which forms the resin, best results are obtained for the monoalkanol-dialkyl-quaternary ammonium substituted alkyl type of anion exchanger (i. e., dimethylethanolamine type precursor) containing. 0.2 to 2.0% chlorine in the copolymer resin, with optimum results thus far With about 1.5% chlorine for 9% crosslinked copolymer resins. With the trialkyl substituted quaternary ammonium substituted alkyl type of anion exchange (i. c., trirncthylamine type of precursor), the chlorine content should preferably be between 0.2 and 3.5%, although better results are obtained at a concentration of 1.0 to 3.0% and optimum results have been obtained thus far at a concentration of about 1.7% chlorine. When the chlorine is introduced by elemental chlorine gas to a monoalkanol-dialkyl-quaternary ammonium anion exchanger, best results are obtained with a chlorine content of from about L5 to 3.0% chlorine, with optimum results at a chlorine concentration of about 2.6%. With a trialkyl quaternary ammonium type of exchanger, the copolymer should contain 0.2 to 4.0% chlorine With optimum results at a concentration of 2.6% chlorine. The halogens. contemplated in the halogenated copolymer resins are chlorine and bromine.

We have observed that the greatest increase in operating capacity is obtained by halogenation subsequent to polymerization of the resin. To date, the greatest increase in operating capacity has been obtained by the use of chlorine gas or sulfuryl chloride as the source of halogen.

In defining the percentage of halogen in the halogenated copolymer resin, in the specification and claims, we mean the amount of halogen substituted on the copolymer resin based on its Weight before it has been halogenated.

By preparing the anion exchange resins of the invention from halogenated copolymer resins containing the prescribed amounts o-f halogen in accordance with the present invention, it is possible to obtain an enhancement of the operating capacity of the resins which is from 10 to 50% of that of equivalent anion exchange resins which do not contain the prescribed and limited amount of halogen. In addition to the increase in operating capacity, other concomitant advantages are usually obtainec'i, such as an improvement in the basicity value (ability to remove weakly acidic anions), an increase in ultimate capacity, as Well as an improved mechanical stability of the resin particles to shattering and breaking after repeated usage and regeneration of the anion exchange resin. The advantages of the present invention accrue only when the halogen content falls within the prescribed limits set forth above. When the maximum limit prescribed for halogen content is exceeded, the advantages of the invention do not obtain and very often an increase in halogen content above the prescribed limit results in an anion exchange resin having poorer operating capacity and other prop erties than an anion exchange resin having no halogen in the copolymer resin.

The mechanism or principle by which the present inven" tion operates is not known to us. Assuming that ali. ot' the halogen present in the copolymer resin is converted to quaternary ammonium groups, which is probably not true, this would not be sufiicient to account for the increase in capacities of the anion exchange resins. Also, presumably a large part, at least, of the halogen is substituted on the aromatic nuclei and this type of halogen substitution is not usually prone to react with amines under the conditions which we utilize. Nor are We certain of Where halogen, when introduced into the resin after polymerization, is substituted or added. Some of the halogen may become substituted on the aliphatic crosslinker...or.onthe polyethylene bridges of thecopolymerresin. In spite .of the lack. of a theory for accounting for theincreased capacity of the resins of the invention, superior results are obtained.

The next step in the preparationof the anionexchange resins of this inventionis the haloalkylation ,ofthe halogenated copolymer resin. This stepinvolves introducing into the copolymer a plurality of bromoalkyl or preferably. chloroalkyl groups. This entails the substitution onto the aromatic nuclei of the copolymer resin, groups having the general formula:

wherein X is chlorine or bromine and n has the same definition as above. While it is contemplated that n may contain from 1 to 4 carbon atoms, it is preferred to employ those compounds having chloromethyl groups substituted in the insoluble copolymer resin because these products are the most reactive. The carbon atoms in the haloalkyl group may be in a straight or a branched chain. The preferred method of haloalkylation is by reactingthe insoluble copolymer resin'with a haloether or a mixture of an *alkyl halide and a halogenacid and a Friedel-Crafts catalyst, such as aluminum chloride, zinc chloride, stannic chloride, etc. One may also haloalkylate by reacting the copolymer resin with an aldehyde anda halogen acid (e. g., paraformaldehyde and hydrochloric acid). Alternately, one may use a dihaloalkane and a Friedel-Crafts catalyst (e. g., ethylene dichloride and aluminum chloride). Methods of chloroalkylating are described in Organic Reactions, vol. 1, chapter 3, page 63 et seq. (1942). it is desirabletohave. several of the haloalkyl groups, which become substituted upon the aromatic nuclei of the 'copolymer resin, for each aromatic nucleus, for each is capable of conversion to an amine group and the greater the number of these, the greater will be the capacity of the anion exchange resin.

In the event that the copolymer resin has been prepared from alkyl substituted monovinyl aryl compounds such as the methyl styrenes, it is possible to prepare the halo alkyl derivative of a halogenated copolymer resin by direct chlorination or bromination of the alkyl substituent on the aryl ring; In this instance, it is desirable to first introduce the small amount of nuclear halogenation (maximum of 4.0%) by halogenating with a nuclear-directing carrier such as iodine, ferric chloride, iron, aluminum chloride, etc. The nuclear directing carrier is then removed from the reaction mixture and halogenation of the alkyl side chain undertaken with elemental. bromine or chlorine. if there is more than a single ,alkyl group for. each aromatic nucleus, a corresponding number of haloalkyl groups will be formed.

The final step in preparing the anion exchange resins of the invention is the amination step to prepare the amino alkyl derivative or the quaternary ammonium alkyl derivative. This reaction is preferably carried out by adding the amine to the haloalkylatcd, halogenated cope.- lymer while the latter is suspended and agitated in a liquid which is a solvent for the amine. The mixture may be allowed to react at room temperature or at elevated temperatures, after which the resin containing the quaternary ammonium salt groups is removed from the liquid reaction medium. If a primary amine is used in the amination in the preparation of the final product, the anion exchange resin will be a secondary amine derivative of the haloalkylated, halogenated copolymer resin. it a secondary amine is used in the amination of the preparation of the final product, the anion exchange resin will be a tertiary amine derivative of the haloalkylated,halogenated copolymer resin. if a tertiary amine is used, the final product will be a quaternary ammonium derivative. If ammonia is used, the final product will be primary amine-derivative. The quaternary ammonium type of anion exchange resin is preferred because it is more highly basic and will remove weaker anions from solution,

Among, the primary andsecondary amines. which may be used for amination are the lower ,alkyl amines, such as propylaminc, ethylene diamine, dimethylamine, diethylamine, dipropylamine and di-n-butylamine; the lower alkanol amines, such as methyl ethanol amine, ethyl ethanol amine, and diethanolamine; the aralkylamines, such as dibenzyl-amine, methylaniline; the polyalkylene polyamines, such as diethylene triamine, triethylene tetraamine and tetraethylene pentaamine; and the cyclic amines, such as piperazine, piperidine and morpholine. Of this group, the polyalkylene polyamines are preferred.

Among the tertiary amines which may be used for amination are free bases, such as amines containing alkyl, aralkyl and alkanol groups. Suitable tertiary amines are typified by the following: trimethyl-,. triethyland tripropylamines, benzyldimethylamine, dimethylethanolamine, methyldiethanolamine, and the like. Trimethylamine and dimethyle'thanolamine are preferred.-

Alternately, but less satisfactorily, one may prepare the quaternary ammonium derivatives of the haloalkylated halogenated copolymer resins by reacting the haloalkylated derivatives with ammonia, primary or secondary amines, followed by treatment of the resulting primary, secondaryor tertiary amine with a quaternizing.

agent. Among the well known group of quaternizing agents are the alkyl halides, such as methyl chloride,

bromide and iodide, ethyl chloride, bromide and iodide,

etc.; dialkyl sulfates, such as dimethyl, diethyl, dipropyl, dibutyl sulfates; epihalohydrins, such as epiehlorohydrin; and alkyl esters of aryl sulfonates, such as methyl toluene sulfonate and methyl benzene sulfonate. Because of the greater cost of reagents, this method is less desirable.

For purposes of anion exchange, it is necessary to first convert the quaternary ammonium salts which are usually obtained from the methods of preparation described above to the correspondingquaternary ammonium hydroxide form'by treating the anion exchange resin with a dilute alkali, such as a 5% solution of sodium hydroxide.

The invention also comprises the novel process for removing anions from an aqueous solution, comprising; contacting the solution withthe quaternary ammonium erated by washing it with a dilute alkali, preferably. sodium hydroxide, which alkali will form a-solublesalt with the adsorbed anions.

In order to disclose more clearly the nature of the.

present invention, specific examples illustrating the preparation of typical compounds will hereinafter bedescribed. This is done solely by way of example and is intended neither to delineate the scope of the invention nor limit the ambit of the appended claims.

EXAMPLE 1 A. Preparation of chlorinated copoly'mer resin A copolymer resin was prepared which consisted of 9% aliphatic crosslinker in the following manner: To about 900 ml; of water heatedtb 60-90 C. was added 259 grams of styrene, 13.6 grams of orthochlorostyrene,

27 grams ethyleneglycoldimethacrylate; and about 1.1

grams of benzoyl peroxide- The mixture was heated for about 12,hours with agitation, after which polymerization. was complete. The resulting product was washed with water and dried at between -130 C. for 3 hours.

Upon analysis, the :chlorine content was. found tube.

The quaternary ammonium amine,

7 B. Preparation of chloromethyl derivative of chlorinated copolymer resin About 200 grams of the chlorinated copolymer resin obtained in part A above was suspended in a mixture of 590 grams of propylene dichloride and 200 grams of monochloromethylether. The mixture was cooled by an external bath to 15 C. and 117 grams of anhydrous aluminum chloride was added over 1 hour at 1520 C. The mixture was stirred at this temperature for an additional 5 hours. It was then poured into a large amount of ice water, the insoluble particles filtered and washed with water.

C. Preparation of dimethylethanolamine derivative of chloromethylated, chlorinated resin The resulting chloromethylated beads obtained in part B above were suspended in 488 grams of water and 248 grams of a 70% solution of dimethylethanolamine in water was added. The mixture was stirred for 5 hours at 50 C.; the quaternary ammonium polymeric salt was then washed with water. The anion exchange resin was regenerated with dilute sodium hydroxide, washed with'water and found to have a basicity value of 19.9 kgr./cu. ft., an ultimate capacity of 23.1 kgr./cu. it, an operating capacity of 19 kgr./cu. it. using 6 lbs/cu. it. of sodium hydroxide as a 5% solution, and a density of 310 g./l. An otherwise equivalent material prepared without the use of orthochlorostyrene had an operating capacity of only 15.5 kgr./ cu. ft. Thus there is obtained an increase in operating capacity of 28.3%. When prepared from a resin containing 7.9% chlorine, an otherwise equivalent anion exchange resin had an operating capacity of only 15.0 kgr./cu. ft.

EXAMPLE 2 A. Preparation of trimethylamine derivative of chlromethylated, chlorinated copolymer resin Approximately 600 grams of wet chloromethylated beads described in part B of Example 1 was suspended in 352 ml. of water and 470 grams of a 25% solution of trimethylamine in water was added. The mixture was stirred at room temperature for 4 hours, filtered and the resin washed with water. Upon regeneration with dilute sodium hydroxide solution, the resin had a basicity value of 16.1 kgr./cu. ft., an ultimate capacity of 25.0 kgr./cu. ft., a density of 288 g./l., and an operating capacity of 11.6 kgr./cu. ft. with a regeneration dosage of 4 lbs/cu. ft. of sodium hydroxide as a 5% solution. An otherwise equivalent material prepared in a similar fashion without of the use of orthochlorostyrene gave upon similar regeneration an operating capacity of only 9.0 kgr./cu. ft.; also, if the chlorine content was 7.9%, an operating capacity of 9.0 kgr./cu. ft. was obtained. Thus there is obtained an increase in operating capacity of 27.4%.

EXAMPLE 3 A. Preparation of copolymer resin A copolymer resin was prepared which consisted of 9% aliphatic crosslinker in the following manner: To about 900 ml. of water heated to 60-90 C. was added 273 grams of styrene, 27 grams of ethyleneglycoldimethacrylate and about 1.1 grams of benzoyl peroxide. The mixture was heated until polymerization was complete and the resulting copolymer was washed with water and dried at about 110-130 C for 3 hours.

B. Preparation of chloromethylated, chlorinated copolymer resin About 220 grams of the copolymer prepared in part A was suspended in 650 grams of propylene dichloride. The mixturewas. heated with "stirring to approximately 60 C. and 20 grams of sulfuryl chloride was added. The mixture was maintained at reflux (approximately 68 C.')

for 20 minutes and cooled to 15 C. with an external ice bath. A sample of the material was removed and found to contain 1.5% chlorine. Approximately 200 grams monochloromethylether was added, followed by 117 grams of anhydrous aluminum chloride, with stirring for one hour at 10-15 C. Stirring was continued for an additional 4 hours whereupon the mixture was poured into a [large volume of ice water, the insoluble particles filtered from solution and washed with water.

C. Preparation of dimethylethanolamine derivative of chloromethylated, chlorinated copolymer resin The chloromethylated beads obtained in part B were suspended in 296 grams of water and 248 grams of a 70% solution of dimethylethanolaminc. The mixture was heated to 50 C. with stirring and the heating and stirring continued for an additional 5 hours. The resulting material was filtered, washed with water and regenerated with a dilute sodium hydroxide solution to produce a material having a. basicity value of 20.1 kgr./cu. ft., an ultimate capacity of 21.1 kgr./ cu. ft., a density of 323 g./l. and an operating capacity of 17.3 kgr./cu. ft. An equivalent unchlorinated material gave an operating capacity of only 15.5 kgr./ cu. ft. with the same regeneration dosage. Thus there is obtained an increase in operating capacity of 11.6%.

Based upon the ultimate capacity value obtained for the anion exchange resin, it is calculated that the copolymer resin contained about 0.77 chloromethyl groups per aromatic nucleus prior to being aminated with dimethyl-ethanolamine.

EXAMPLE 4 A. Preparation of copolymer resin A copolymer resin consisting of 15% orosslinker was prepared in the following manner: About 1800 ml. of water was heated to about 6090 C. and to this was added a premixed solution of 510 grams of styrene, grams of ethyleneglycoldimethacrylate and about 2.2 grams of benzoyl peroxide. The mixture was stirred at about 6090 C. until polymerization Was complete. The beads were filtered, washed with water and dried at about C.

B. Preparation of chloromethylated, chlorinated copolymer resin One hundred and seventy-eight grams of the dry polymer obtained in part A was suspended in 460 grams propylene dichloride and 26.7 grams of sulfurytl chloride was added. The mixture was heated at 50 C. for 30 minutes, then cooled by an external ice bath to 10-15 C. Upon analysis, the halogenated resin was found to contain 3.8% chlorine. About 178 grams of chloromethylether was added, followed by 104 grams of anhydrous aluminum chloride over a period of 2 hours. The mixture was stirred for an additional 4 hours at 10-15 C. The beads were then quenched in ice water, washed and filtered.

C. Preparation of quaternary ammonium derivative of chloromethylated, chlorinated copolymer resin The chloromethylated beads obtained in part B were suspended in 239 grams of water and 200 grams of a 70% solution of dimethylethanolamine in water was added. The mixture was heated to 50 C. for 6 hours, neutralized with sulfuric acid and the propylene dichloride distilled off at 90 C. The resulting resin had a basicity value of 17.3 kgr./cu. ft., an ultimate capacity of 21.0 kgr./cu. ft., a density of 296 g./l. and an operating capacity of 17.4 kgr./cu. ft. using a regeneration dosage of 6 lbs/cu. ft. of sodium hydroxide as a 5% solution. An otherwise equivalent material prepared without the use of 'sulfuryl chloride had an operating capacity of only 14.4 kgr./cu. ft. under the same regeneration dosage.

9 Thus there was obtained an increase in operating capacity of 20.8 70".

EXAMPLES A. Preparation of chloromethylated, chlorinatedjcopolymer resin A copolymer containing ethyleneglycoldimethacrylate crosslinker in the amount of 9%" was prepared in the same manner as described inpart A of Example3. Approximately 220 grams of the copolymer was suspended in 650 grams of propylenedichloride. The mixture was heated with stirring to 50 C. and a crystal of iodine dissolved therein. A slow stream oichlon'ne was then introduced for 30 minutes and stopped when 4.4 gins. of chlorine had been introduced and the mixture cooled to 15 C. With an external ice bath. A sample of the material was removed and found to contain 2.6% chlorine. Approximately 200 grams mon chloromethylether was added and 117 grams of anhydrous aluminum chloride was added with stirring for one hour at l-15 C. Stirring was continued for 4 hours whereupon the mixture waspoured into icewater and the particles filtered from solution and washed with Water.

B. Preparation of quaternary ammonium derivative of chloromethylated, chlorinated 'copolymer resin The chlorinated, chlloromethylated beads obtained above were suspended in.239 gramsof. water and 250. grams of 70% solution of dimethylethanolamine in water was added. The mixture was heated to 50" C. for 6 hours and neutralized with sulfuric acid and thepropylene dichloride distilled off at 90 C. The resulting resin had a basicity value of 21.5 kglz/cu. ft., an ultimate capacity of 22.1 kgri/ cu. ft., a density of 304 g./l. and. an operating capacity of 17.5 kgr./ cu. it. using aregeneration dosage of 6 lbs/omit. of'sodium hydroxide as a 5% solution. An otherwise equivalent material prepared. without the use of chlorination had an operating capacity of only 15.4 kgr./cu. ft. with 200p. p. m. FMAwater containing 17 p. p. m. silica. With.l5.5% chlorine in the copolymer resin, the operating capacity was 11.6 kgr./ cu. feet.

EXAMPLE 6 A. Preparation of quaternary ammonium derivative of chlorinated, ehloromethylated copolymer Approximately 600 grams of chlorinated, chloromethylated beads obtained in part A of Example 5 was suspended in 352 ml. of water and 470 grams of a 25% solution of trimethylamine in water was added. The mixture was stirred at room temperature for four hours, filtered and the resin washed with water. The resulting anion exchange resin was found to havea superior operating capacity over an otherwise equivalent material which had not been chlorinated.

EXAMPLE 7 A. Preparation of chloromethylated, chlorinated copolymer About 220 grams of theicopolymer prepared in part A of Example 3 was suspended in 650 grams ofpropylene dichloride. The mixturewas.heated'withstiriing toapproximately 60 C. and20 grams of sulfuryl chloride.

was added. The mixture was maintained at reflux (ap proximately 68. C.) for 25 minutes and cooled to 15 C. with an external ice bath. Aisample ofthe material was removed and found to contain 1.7%" chlorine. Ap proximately 206 "grams monochloromethylether was added, followed by 117 grams of anhydrousa lurninum chloride with stirring for one hour at 10-15 C. Stirring was continued for anadditional 4 hours whereupon the mixture was poured into a large volume of "ice water, the insoluble particles filtered from solution and washed with water.

10 B. Preparation of quaternary ammonium derivative of chloromethylated,lchlorinated copalymer Approximately 600' grams of wet chloromethylated, chlorinated beads prepared as in part A above was suspended in 352 ml. of water and 470 grams of a 25% solution of trimethylamine was added. The mixture was stirred at room temperature -for-4=hours, filteredand the resin washed with water. Upon regeneration: with dilute sodium hydroxide solution, the resinhad a 'basicity value of 17.0 kgr./cu. ft., an ultimatecapacity of 22.2.kgr./cu. ft, a density of 271 g./l. and operatingzcapacity of 14.0 kgr./ cu. ft, with a regenerationdosage of 4 lbs/cu. ft. of sodium hydroxide in 5% solution; An equivalent material prepared in a similar fashion without chlorination by sulfuryl chloride gave upon similar regeneration an operating capacity of only 9.0 kgr./cu. ft. Thus there is obtained an increase in operatingqcapacity of 56%.

EXAMPLE 8 A. Preparation of tetraethylenepentamine derivative of cltloromethylated, chlorinated copolymer resin A copolymer was prepared in accordance with the procedure of Example 1A in which ortho-chlorostyrene was present in the copolymer to theextent of 5% of the weight of styrene. Ethyleneglycoldimethacrylate was present as a crosslinker in the amount of 4% by weight of the copolymer resin. This gave a copolymer resin containing about 1.5% chlorine. The dry polymer was ch loromethylated in the same fashion described in Example 1B. 400 grams of wet chloromethylated beads was suspended in 400 ml. of benzene and-427 grams tetraethylenepentamine was added. The mixture was heated under reflux for 6 hours and the-solvent removed. The material had an ultimate capacity of 37.6: kgr./cu. ft.', a density of 33.6 g./l. and anopcrating. capacity of 34 kgn/cu. ft. using 6 lbs/cu. ft. of sodium. carbonate in a 5% solution. An otherwise equivalent material prepared without orthochlorostyrene in:the copolymer had an operating capacity of only 31 kgn/ cu. ft.

The examples describe the-preparation of anion exchange resins based on styrene and ethyleneglycoldimethacrylate in which the ethyleneglycoldirnethacrylate crosslinker is present in amounts of 4, 9. and 15% of the copolymer resin. However, it should be understood that other proportions of crosslinlrermay be used and, as has beenstated above, other polymerizatesthan that of styrene-and ethyleneglycoldimethacrylate may be used with success. Also, other amounts of-halogen-may be used if within the range specified above in the specification. By resorting to the teachings of the present specification and the general knowledge common to the art, anion exchange resins of halogenated copolymer resins as contemplated by the present invention may be prepared.

EVALUATION TESTS Certain data are given for the products prepared in the above examples which are of value in assessing the usefulness of highly basic anion exchange resins. The method used for determining those values which are not the subject of standardized tests is described below.

As used in the examples and elsewhere in this speoi fication, the term basicity value (sometimes referred to as salt-splitting capacity) is a measure of the capacity of the anion exchange resin to removethe anions of weak acids. Sincethe value of a highly basic anion exchange resin may often reside in its ability to remove the anions of weak acids, as well as those. of strong acids, this is a critical value ofthe performance. of any basic anion exchange resin. As expressed here, this value is obtained by passing 270 ml. of a 0.75 normal sodium hydroxide solution through a 16 mm. column containing 4-0 ml. of

the anion exchange resin at a flow rate ofapproximately,

The resin bed is rinsed as free as possible of phenolphthalein alkalinity with distilled water. 750 ml. of 0.5 normal sodium chloride solution is next passed through the resin bed at a flow rate of 7.5 ml. per minute. The column is washed with distilled water. The effluent and washings from the sodium chloride treatment are collected, mixed and titrated with 0.02 normal sulfuric acid solution to a methyl orange endpoint. Since the strongly basic anion exchange resin will remove chloride ion from the sodium chloride solution and convert sodium chloride to sodium hydroxide, this determination permits the calculation of the sodium chloride converted to sodium hydroxide giving the basicity value capacity of the anion exchange resin. This sodium chloride splitting value is expressed in kilograins of calcium carbonate per cubic foot of anion exchange resin. Resins having a high basicity value will have a high capacity for the removal of weak acids, such as silicic acid and carbonic acid from solutions.

The term ultimate capacity used in the examples and elsewhere in the specification is determined by placing 40 ml. of resin, which has first been placed in the chloride form by passing an excess solution of dilute hydrochloric acid over the resin followed by washing with water, in a column of 16 mm. size and through this column is passed 1000 ml. of 0.75 normal sodium hydroxide at the rate of ml./min. The resin bed is then washed free of phenolphthalein alkalinity with distilled water. Next 800 ml. of 0.25 normal hydrochloric sulfuric acid solution (a ratio of 1.5 parts of hydrochloric to 2.5 parts of sulfuric) is passed through the resin bed at a flow rate of mL/min. Next 700 ml. of distilled water is passed through the tube. The effiuent is collected and mixed and an aliquot is titrated to determine the residual acid. From this, the total amount of acid absorbed may be computed in terms of kgr./cu. ft. of calcium carbonate which gives the total or ultimate capacity of the resin.

It is desirable that for use as anion exchange resins, the quaternary ammonium derivatives of the copolymers of the invention be converted to the corresponding quaternary ammonium hydroxide derivatives. This result is accomplished by passing a dilute aqueous solution of an alkali, such as sodium hydroxide, over the quaternary ammonium derivative of the copolymer.

The terms and expressions which we have employed are used as terms of description and not of limitation, and we have no intent-ion, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. An anion exchange resin of improved operating capacity, which comprises the product produced by first haloalky lating a halogen-containing copolymer resin comprising a halogen-containing polymerizate of a vinyl aromatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker compound, said [halogenated copolymer resin containing between about 0.2% and 4.0% halogen before being haloalkylated, said haloalkylated product con taining at least about 0.77 haloalkyl groups per aromatic nucleus, and then treating the resulting haloalkylated, halogenated copolymer resin with an amine.

2. An anion exchange resin of improved operating capacity, which comprises the product produced by first chloromethylating a halogen-containing copolymer resin comprising a halogen-containing polymerizate of a. vinyl aromatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker compound, said halogenated copolymer resin containing between about 0.2% and 4.0% halogen before being chloromethylated, said chloromethylate d product containing at least about 0.77 chloromethyl groups per aromatic nucleus, and then treating the. resulting chloromethylated, halognated copolymer resin with an amine.

3. *An anion exchange resin as described in claim 2, in which the halogen is chlorine.

4. An anion exchange resin as described by claim 3 in which the amine is an alkanolamine.

5. An anion exchange resin as described in claim 3 in which the vinyl aromatic hydrocarbon forms a predominant part of the copolymer resin.

6. An anion exchange resin as described in claim 3 in which the vinyl aromatic hydrocarbon comprises 60% to 99.9% on a molar basis of the copolymer resin.

7. An anion exchange resin as described in claim 3 in which the monovinyl aromatic hydrocarbon is styrene.

8. An anion exchange resin as described in claim 3 in which the diolefinic unsaturated aliphatic crosslinlter is a member selected from the class consisting of divinyl su-ltone, divinyl iceton'e, vinyl maleate, ethylene dimethylacrylate, vinyl ethinyl hydrocarbons, vinyl esters of acrylic, methacrylic and ethacrylic acids, divinyl esters of di basic acids and acrylic diesters of an aliphatic polyhydric alcohol.

9. An anion exchange resin as described by claim 3 in which the amine is a tertiary amine.

10. An anion exchange resin of improved operating capacity, which comprises the product produced by first halogenating a copolymer resin comprising a polymerizate of a vinyl aromatic hydrocarbon and a dioleiinic unsaturated aliphatic crosslinker compound until the co polymer resin contains between about 0.2% and 4.0% halogen, then haloalkylating the resulting halogenated copolymer resin, and finally treating the resulting haloalkylated, halogenated copolymer resin with an amine.

11. An anion exchange resin of improved operating capacity, which comprises the product produced by first chlorinating a copolymer resin comprising a polymerizate of a vinyl aromatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker compound until the copolymer resin contains between about 0.2% and 4.0% chlorine, then chloromethylating the resulting chlorinated copolymer resin until it contains at least about 0.77 chlorornethyl groups per aromatic nucleus, and finally treating the resulting chloromethylated, chlorinated copolymer resin with an amine.

12. An anion exchange resin as described by claim 11 wherein the chlorination is accomplished by elemental chlorine.

13. An anion exchange resin as described by claim 11 wherein the chlorination is' accomplished by a chlorinating agent.

14. An anion exchange resin as described in claim 13 wherein the chlorinating agent is sulfuryl chloride.

15. An anion exchange resin as described in claim 11 wherein the amine is an alkanolamine.

16. An anion exchange resin as described in claim 11 wherein the amine is a tertiary aliphatic amine.

17. An anion exchange resin as defined by claim 1 wherein the halogenated copolymer resin is produced from at least two vinyl aromatic hydrocarbons, one of which contains nuclear substituted halogen, and a dielefinic unsaturated aliphatic crosslinker compound.

18. An anion exchange resin as defined by claim 3 wherein the halogen is chlorine and the chlorinated copolymer resin is produced from at least two vinyl aromatic hydrocarbons, one of which contains nuclear substituted chlorine, and a diolefiuic unsaturated aliphatic crosslinker compound.

19. A method of removing anions from solutions which comprises bringing such solutions .into contact with the anion exchange resin of claim 1.

20. A method of removing anions from solutions which comprises bringing such solutions into contact with the anion exchange resin of claim 3.

21. A method of removing anions from solutions which comprises bringing such solutions into contact with the anion exchange resin of claim 10.

22. The process of producing an anion exchange resin 13 which comprises first haloalkylating a halogen-containing copolyrner resin comprising a halogen-containing polymerizate of a vinyl arc-tnatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker compound, said halogenated copolymer resin containing between about 0.2% and 4.0% halogen before being halogenated, until the halogen-containing copolymer resin contains at least about 0.77 haloalkyl groups per aromatic nucleus, and then treating the resulting haloalkylated, halogenated copolyrner resin with an amine.

23. The process of producing an anion exchange resin which comprises first chloromethylating a chlorine-com taining copolyrner resin comprising a chlorine-containing polymerizate or" a vinyl aromatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker compound, said chlorine-containing copolymer resin containing between about 0.2% and 4.0% chlorine before being chloromethylated, until the chlorine-containing copolymer resin contains at least about 0.77 chloromethyl groups per aromatic nucleus, and then treating the resulting chlorornethylated, chlorine-containing copolymer resin with an amine.

24. The process of producing an anion exchange resin which comprises first preparing a chlorinated copolymer resin by copolymerizing two or more mono-vinyl aromatic hydrocarbon compounds, one of which compounds contains nuclear substituted chlorine, with a diolefinic unsaturated aliphatic crosslinker compound, with the resulting copolym er resin containing from about 0.2 to 4.0% chlorine, next haloakylating the resulting chlorine-containing copolymer resin until it contains at least about 0.77 haloalkyl groups per aromatic nucleus and then treating the resulting product with an amine.

25. The process of producing an anion exchange resin which comprises first halogenating a copolymer resin comprising a polymerizate of a vinyl aromatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker compound until the copolymer resin contains between about 0.2% and 4.0% halogen, next haloalkylating the resulting halogenated copolymer resin, and finally treating the resulting haloalkylated, halogenated copolymer resin with an amine.

26. The process of producing an anion exchange resin which comprises first chloninating a copolymer resin comprising a polymerizate of a vinyl aromatic hydrocarbon and a diolefinic unsaturated aliphatic crosslinker C0111- pound until the copolymer resin contains between about 0.2% and 4.0% chlorine, next chloromethylating the resulting chlorinated copolymer resin until. it contains at least about 0.77 chloromethyl groups per aromatic nucleus, and finally treating the resulting chloromethylated, chlorinated copolymer resin with an amine.

27. A process as described by claim 26 in which the amine is a member selected from the class consisting of an alkanolamine and a tertiary aliphatic amine.

References Cited in the file of this patent UNITED STATES PATENTS 2,597,440 Bodarner May 20, 1952 2,614,099 Bauman Oct. 14, 1952 2,632,001 McMaster Mar. 17, 1953 2,702,795 Gilwood Feb. 22, 1955 FOREIGN PATENTS 694,778 Great Britain July 29, 1953 OTHER REFERENCES Norrish et al.: Proc. Royal Soc. (1937), A163, pages 205-207 (article runs to page 220). 

1. AN ANION EXCHANGE RESIN OF IMPROVED OPERATING CAPACITY, WHICH COMPRISES THE PRODUCT PRODUCED BY FIRST HALOALKYLATING A HALOGEN-CONTAINING COPOLYMER RESIN COMPRISING A HALOGEN-CONTAINING POLYMERIZATE OF A VINYL AROMATIC HYDROCARBON AND A DIOELFINIC UNSATURATED ALIPHATIC CROSSLINKER COMPOUND, SAID HALOGENATED COPOLYMER RESIN CONTAINING BETWEEN ABOUT 0.2% AND 4.0% HALOGEN BEFORE BEING HALOALKYLATED, SAID HALOALKYLATED PRODUCT CONTAINING AT LEAST ABOUT 0.77 HALOALKYL GROUPS PER AROMATIC NUCLEUS, AND THEN TREATING THE RESULTING HALOALKYLATED, HALOGENATED COPOLYMER RESIN WITH AN AMINE. 